连续打印文件 Linux 终端的最后一行
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continuously print the last line of a file Linux termin
提问by yaegerbomb
Two questions, but only stuck on one. Feel that I need the first one so someone can help me make sense of it.
两个问题，但只停留在一个。觉得我需要第一个，以便有人可以帮助我理解它。
4) Use cat and /dev/null to create an empty file.
4) 使用 cat 和 /dev/null 创建一个空文件。
5) Start a background process that continuously prints the last line of the file created in #4..
5) 启动后台进程，连续打印#4..中创建的文件的最后一行。
So what i did for number 4 was:
所以我为 4 号做的是：
cat /dev/null > emptyfile
This created an empty file. Okay so I am happy with that. The next question however confuses me. How can I read the last line of an empty file? Better yet how do I continuously do this? Running it in the background isn't a problem. Anyone have any ideas? We haven't covered scripting yet so I don't think that plays a role. As always, thanks for the help.
这创建了一个空文件。好的，所以我很高兴。然而，下一个问题让我感到困惑。如何读取空文件的最后一行？更好的是我如何不断地做到这一点？在后台运行它不是问题。谁有想法？我们还没有介绍脚本，所以我认为这不起作用。一如既往，感谢您的帮助。
采纳答案by Kim Burgaard
Use the UNIX command "tail" with the -f option. That will continuously print out contents from the file to the terminal as it is added to the file.
使用带有 -f 选项的 UNIX 命令“tail”。当它被添加到文件时，这将不断地将文件中的内容打印到终端。
Example:
例子：
tail -f emptyfile
You can terminate the tail process by typing Ctrl + C.
您可以通过键入 Ctrl + C 来终止尾部进程。
回答by pistacchio
doesn't tail -f FILE_NAMEhelp?
没有tail -f FILE_NAME帮助？
回答by Ignacio Vazquez-Abrams
tailwith watchor a loop with a delay.
tailwithwatch或有延迟的循环。
Also, neither catnor /dev/nullare required.
此外，既不需要cat也不/dev/null需要。
> emptyfile
tailand watchexample:
tail和watch例子：
watch tail -n 1 log.txtwill always show the last line of the log file. Default interval in watchis 2 seconds.
watch tail -n 1 log.txt将始终显示日志文件的最后一行。默认间隔watch为 2 秒。
